Electron tube



Jan. 4 192 7. I w. DAUMANN ELECTRON TUBE Filed Jan. 16. 1923 g W/u/a/y p/qu/ @J o m Patented Jan. 4, 1927.

UNITED STATES PATENT OFFICE.

WILHELM DAUMANN, OF HAMBURG, GERMANY, ASSIGNOR TO C. H. F. MI ILLER, RNTGENRbHRENFABRIK, OF HAMBURG, GERMANY, A CORFORATION OF GERMANY.

ELECTRON TUBE.

Application filed January 16, 1923, Serial No. 613,045, and in Germany January 14, 1922.

My invention relates to improvements in electron tubes. As is known in the art, a discharge of electric energy may occur between electrodes in a high vacuum-where ionization of the gas is impossible-without aux liaries such as an incandescent cathode etc. The condition for such a discharge 1s that the electrodes should be at a sufficiently short distance from one another. The discharge is a pure electron discharge and may therefore be used technically for all purposeswhere cathode rays are employed.

The discharge is assisted by sharply curved faces of the electrodes, such as edges, points, etc.

In my invention, I make the-sald sharply curved faces from at least one thin wire the enveloping surfaces of which face the electrode. In its most primitive constructlon, my improved device therefore comprises a metal plate anode arranged in a high vacuum electron tube, and a thin wire cathode secured by any convenient means at a short distance from said anode, its enveloping surface facing the anode. Experience has demonstrated that a thin wire supported in this manner at a distance of a few millimetres from a plate is able to effect a discharge of the kind described, if a suitably high voltage be. impressed. I

The advantages of my novel device are as follows:

1. The difficulty of constructing the active faces of cathodes in the shape of edges, points or the like, is removed by using wire which readily lends itself to any desired form.

2. In my improved device, the radii of the active faces of a wire can be duplicated with any desired degree of accuracy so that with my improved device I am able to manufacture tubes having exactly identical electric properties.

3. The complete degasifieation ofv the elec trodes required in tubes of the kind described may readily be effected in the cathode by means of currents conducted through the wires.

4. The wires may be usedas incandescent wi res as well, so that the discharge tube may also be operated as an incandescent'cathode tube, an important advantage, particularly when degasifying the other electrodes, for

instance the anode.

In the case of high voltages, such as are required in the generation of very hard Roentgen rays, for instance, the wires having the sharply curved faces should be so arranged as not to be torn by the strong elecirostatic attraction then arising. To this end, in my improved device, I form the Wires as sharply curved bends having radii of a few millimetres, and facing the other electrode. The tensile stress on the wires is reduced so considerably by these means that the wires are not torn with the Volta es occurring, as demonstrated by theory an practical experience.

In the drawings affixed to this specification, I have illustrated several devices embodying my invention by Way of example. In the drawings- Fig. 1 is an elevation showing a high vacuum tube provided with my improved "device, and its connections,

Figs. 2 and 3 are elevations illustrating two modified tubes, partly broken away, and

Fig. 4 is an isometric view of a portion of the tube shown in Fig. 3.

Referring to Fig. 1, this tube comprises a plate 1 which may be circular and, facing said plate, a curved wire 2 which is secured to the leads 3. 4. The curved wire 2 is in a plane at right angles with the plate 1 from which its vertex is ata distance of a few millimetres.

For degasifying the wire 2, current is conducted through it from a heating battery 5 by means of the leads 3, 4. The plate 1 is degasified by the electrons emanating from the hot wire 2 and are projected on to the plate 1 with the aid of the high voltage generator .6.

For higher loads, the anode plate 1 is made larger and asystem of wires is arranged facing it.

In order to utilize also the cathode rays which, as experience shows, emanate laterally, dished or hollow anodes are provided in the tubes illustrated in Figs. 2 and 3, the I bends 0f the wires being arranged in said hollow anodes.

As shown in Fig. 2, the anode 7 is in the shape of a hollow hemisphere and three bent wires 8 are arranged in it the bent portions of which extend in principal planes of the sphere and substantially concentrically toit. In the tube illustrated in Figs. 3 and 4, the anode 9 is a semicylinder and in it are arranged a lurality of wires 10, curved as described, w ich extend in lanes at 'rlght angles with the surface of said cylinder and .itS axis and are supported by wires 11 embedded in an insu ated member 12 at the cathode end of the tube.

In the tubes illustrated in Figs. 2 to 4, the curved wires 10 are connected in series with current leads 13 and 14 so that they can be heated-Ito incandescence by means of currents conducted through them, when required, so as to degasify the wires themselves and to be employed as source of electrons for degasifying the anode by electrons projected on to it.

I claim:

A vacuum tube comprising an evacuated envelope having re-entrant stems, a hollow anode supported by one of said stems, a filamentar cathode closely ad'acent said anode an supported by the ot er of said stems, said cathode being com esed 'of'a series of hair-pin-like loops t e ends of which are embedded in its supporting stem, portions of the loops being connected in series by connecting links.

In testimony whereof I hereunto aflix my nature;

WILHELM DAUMANN. 

